Just to add some additional information, there are two lines of Osmocote products, professional and consumer.
The professional product line is a slightly different formulation (mainly less calcium and magnesium) and is available in different release patterns such as Hi-Start , Standard, and Lo-Start. There are also different four different longevity ratings rantings available, 3-4 mo. 5-6 mo. 8-9 mo. and 12-14 mo., depending on the release pattern. The smallest package I've found the professional line in is 50 lb. bags.
The professional side of The Scotts Miracle Grow Company (Scotts Professional) was purchased by ILC Specialty Fertilizers back in February and has been sold under the Everris brand name since May.
The consumer product line that we are familiar with in Home dePot etc. (Which includes Osmocote Plus in the 4.5 lb. jug) was an off-shoot of the professional line. While the Scotts professional business group was sold, part of the deal was that The Scotts Company retained the rights to market the consumer Osmocote line of products. The American consumer line of Osmocote products has been distributed by Bloomington Brands LLC since 2003.
The I suspect the fact that Home dePot has stopped carrying the OC+ product line was merely a decision made by their buyers since they still carry the regular Osmocote line. If I were to guess, I'd say it didn't sell as well because it was more expensive than the regular stuff.
If you go to the Osmocote Plus page on Scotts' website they have a locate retailer option so you can see who carries it near you. Most Ace hardwares and True Values as well as garden centers around me carry it, but if they are out they probably won't be getting more in until spring (at least in my cold-ass part of the country). Amazon also has it available from several suppliers.